Air tube and shock absorber for resilient wheels for vehicles



Aug. 7, 11923. mwms W. DRURY AIR TUBE AND saocx ABS'ORBER FdR REILIENT WHEELS FOR VEHICLES Filed June 21. 1921 2 Sheets-Sheet 1 Hal Au 7, 1923. "il mmm W. [DRURY AIR TUBE AND SHOCK, ABSORBER FOR RESILIENT WHEELSFOR VEHICLES Film J 2111921 2 sheets sheet 2 till l utented Aug HD2330 h pltcatton flied June ca, 1.9%. 179285.

To all whom may concern:

Be known that Wrrnram @R'URY, a sub ject of the King of Great Britain and 1" e land, residing at it) Lena Gardens, db-epherds Bush ltoad Hammersinith, in the county of London, En land, has invented certain new and useful niprovements in Tubes and Shock Absorbers for Resilient W heels for Vehicles, of which the following is aspecification.

This invention has relation to improvernents in air tubes (and shock absorbers) tor pneumatic tires "for vehicle wheels and has for its object to provide a tube and shoclr absorber adapted to minimize punctures and to up a certain percentage of air pres.

sure and also the stress and. strain usually borne by the ordinary tire outer casing" An inflated but non-stretched ordinary air tube (used for any given size) when new is of similar circurnierence and diameter to the inside circumference and diameter oi? the outer cover that receives the tube, so that immediately the tube is expanded it is pressed hard and test against the inside of the outer cover so that it a pressure of air say 75 lbs.'-to square inch is forced into the tube the whole oi this pressure is borne by the cord or tabric casing of the tire and not by the tube.

For an outer cover or a given inner diameter, l employ an inner tube of my improved construction, which, before inflation, is sit smaller cross section than the interior oil the outer cover, the base of the tube being of a substantial thickness and preferably shaped to fit closely to the inner surface of the beaded or other edges oi the cover, while the side walls of the tube are thinner having a thickness of say about it otan inch upto about the center oi? the height of the tire on either side, and from these points the thiclmess of rubber radually until the crown or tree portion of the tube will have an average thickness of, say, about 1" to it", the interior or the tube being somewhat of an oval or flat topped egg sha e in cross section, For commercial vehic es motor lorries and omnibuses the tube will be of suficient. thickness at all points for the load the tire has to carry. The tube may, in some cases, be split longitudinally and headed edges may be provided thereon to engage 'strengtheningor connecting: rings or girders as will be described. Furthermore ll may provide suction cups or recesses increases in the outer tread portion. or crown of the J 7 tuoe. The tube or shock absorber to contain air or other cushioning fluid is preferably moulded somewhat peanshaped in its cross sectional contour for heeded edge tires,'and ior straight sided tires the tube is moulded to approximately fit the base oi the cover and rirn.

The cubic capacity or this air chamber before inflation will be about one-third or? the cubic capacity of an ordinary tube a similar size tire. In order to force the tube age inst the inside walls and crown of the cover a considerable air pressure is required to be forced into the tube before it is sufficiently inflated to press against the sides and crown of the cover, so that the cubic capacity of the tube after it has been fully in- :tlated to press against the sides and crown of the cover, will be increased to the extent of about two-thirds the cubic capacity of an ordinary thin inner tube. When the tube has been pressed against the sides and crown of the cover it is in a very high state of tension and very resilient and does not lie dead or inert in the outer cover, for although an air pressure of say 75 lbs, to the square inch may be shown on the pump gauge there is really only actual pressure of about 50 lbs. on the outer cover the remaining 25 lbs. pressure being taken up by the tube he tore reaching the sides and crown of the cover. Inna. cross section will carry aworking loader M15 lbs. weight, with a pressure oi:

'50 lbs, per s uare inch on the tire the remaining 25 l s. pressure required to carry the above weight beingborne by the tube, so that although 1415 lbs wei ht is carried jointly by the outer'cover an lbs. pressure per square-inch is on the walls and crown ot the coverin other words, an ordinary tire of 135 nun. cross section will have a strain of 75 lbs, air pressure against its cover to enable it to carry a working load of 14:15 lbs. weight. The same cover fitted with my improved tube will only be subjected to an air pressure and strain of 50 lbs, per square inch to car the same weight and load. This is ve important as under Underthese conditions a tire oi: 135

such conditions the tire will have an inand will also minimize the risk of puncture to these larger tires while also giving considerably increased mileage.

In the accompanying drawings Figure 1 shows a section through a cover with one form of my improved inner tube in position before inflation, while Figure 2 is a similar view with the inner tube fully inflated. F igures 3 and 4 show modifications and Figure 5 shows a form of metal locking ring for the edges of a circumferentially split inner tube.

In carrying this invention into eifect according to one method, I build up a tube on a suitably shaped mandrel which may be annular' or straight; if annular I prefer to have the mandrel formed sectionally and in such a way that the tube can be taken away from the mandrel without being damaged. When the tube has been built up or otherwise shaped as would be-thecase if produced by forcing the rubber through "a suitably shaped die, it is then placed in a mould and ressed to its required shape and thickness; t e tube with its mandrel is then taken out of the mould and the rubber split open at the base (as shown at a in order to take out the mandrel.

I-t will be seen that in its unexpanded form the base of the pear-shaped tube A is approximately of the same shape as that produced by the inner walls of the edges of the tire cover B and the central part of the rim 0. This similarity in shape extends about one third of the height of the tube A. From this point a to the crown a on both sides, the outer periphery of the tube A lies at some appreciable distance from the corresponding inner surface of the cover B, so that there is a considerable free space d (Fig. 1) between the inner tube A and the outer cover B from about the point a to the point a. This Space may be about 1} to about 1} an inch according to the size of tire.

When the inner tube A is inflated the internal air pressure produced therein is not at first transmitted to the outer cover B and it is only when the expansion of the tube A is such as to cause it to come into contact with the inner surface of the outer cover that the latter is subjected to the inflation pressure. Thus if the total'pressure is say 75 lbs; to the square inch, 25 lbs. may be taken up in the expansion of the inner tube and only 50 lbs. by the outer cover. -These figures are merely used asan example as the proportion may in practlce be different according to they size and thlckness of Wall of the inner tube.

The materials of the inner tube will, under inflation, stretch most at its thinnest places, i. e., at about the points a, a while the crown will be very little expanded. The

resiliency and liveliness of the tire will consequently be at the sides, where most required, while the comparatively unstretched crown will be better able to resist punctures than would otherwise be the case.

Instead of making the inner tube in the form of a. closed tube, it may be split longitudinally, as shown at a? in Figures 3 and 4. In that case a thin rubber tube D can be placed in the split tube which is then placed in the mould for vulcanizing, and, after expansion sulficient to cause it to o press against the inner surface of the tube A, and the latter to press against the inner surfaceof the mould is vulcanized thereto. When 'the'tube has been sufficiently vulcanized it will be found that the thin tube has become one homogeneous part of the thicker tube and cannot be separated. Instead of using a complete inner thin rubber'tube D, I may employ only a' strip or a section, say a foot or so long, to carry the valve for inflation of the inner tube. The edges (1' of the inner tube can be specially shaped and provided with internal looking or anchoring means to hold the edges securely together after the thin tube or lining has been inserted. An example ofthis construction is shown in Figure 4 wherein the inner edges (2 of the tube A are provided with lips or beads a A ring E of vulcanite, stiff rubher, or metal having corresponding flanges or projections e is then inserted-after a thin rubber tube D has been laced in the inner tube Aso that 'itsanges 6 engage with the beads a on the inner tube, and the tube is then ready to be placed in a cover and inflated.

In another form, I simply take a band or ring of cured rubber suitably shaped and fitted with an inflating valve and place this within the split tube so as to cover the inside meeting edges thereof and then place the whole in the mould and vulcanize it to one or both edges of the tube.

Before joining up the tube at the base after having been split circumferentially, I

may place in the base portion of the tube a circular girder of resistant material, such as ebonite, aluminium or other metal, in one or more sections and of suitable shape such as I shape to receive the edges of the inner tube, and provide this girder with a number of perforations in its web, so that when the tube is vulcanized and taken out of the mould it has a strong unyielding base which forms an anchorage. This construction is being pertoreted et f in its web 19, When the tube is vulcenized the rubber runs through these oerforetions so thnt the girder is firmly locke in place. llmey ulso provide the trend or crown portion of the tube with e, suiteble number of suction cups or recesses of nround its outer periphery (see Figure 3}, these on s being flush with the outer periphery of t e tube en thnt creeping to e, greet extent will he prevented.

Whet l eleim end desire to secure by Letters Petent is:

i. A pneumetio tire consisting of n cnsing fiend e, rim ettuched thereto, end en enclosed sir-tight inner tube ot resilient materiel substentielly smeller in cross-section then the internel diemeter oi the tire-rinsing end he ingn well of substnntiel thiclmess to render it selt-susteining, the trend end rim portions being thickened and 'tttpfilfitl gredueliy into thinner side portions oi the well whereby when snid inner tube is iniinted it wiil tehe up esubstentiel pert of the internnl ore i eee eee sure end thus muterinlly relieve the rinsing of bursting pressure.

2. A pneumatic tire embodying n tlexible cnsing and e rim uttmhed thereto end en enclosed nintight inner tube made wholly oi elestic materiel end which when uninfleted is substentinlly smelter in diemeter than the interior diemeter or the eesing, seid inner tube having its well of suhstentiel thickness to render it selt-susteining the side wullsbeing thinner than the trend end rim portions of the well, whereby when seid inner tube is infleted it will relieve the cesing mnterielly of internal pressure end whereby, else, the greatest degree of? stretch in the inner'tube will occur in seid thinner side wells end thereby increase their resiliency.

lln testimony whereoi ll ufin my signnture in presence of two witnesses.

WILLIAM lIllPtllThY, Witnesses:

Hnnonn lloneml ELKJINGTQN, lftonnnr Wmrirmnu 

